Valve shims...

[running_sideways]

Alright I've got an issue finally got the bottom end built top ends on everything going awesome
Till I wanna put the cam in and I'm missing a valve shim. I'm running a tomei pon cam been thinking about running dual guides but didn't have the cash...well now I might as well sense one of them ran away...my question to you is what sizes should I order?? Also running hydro lifters


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[TheRealSy90]

Originally Posted by running_sideways

my question to you is what sizes should I order??

YOU need to measure the lash between the camshaft lobe (with valve closed) and the top of the valve stem, and subtract the clearance you want. This is how you determine your shim thickness.


For dual guides, OEM guides are all the same size. Many people run dual oem guides with no issues at all.
However if you want, Tomei offers guide shims in different thickness than the OEM guides.
If they don't have a thickness you need you can order one larger and shave it down, or there's a company in Australia that can make tool steel guide shims to your specified size.
And remember to clearance the arm of the rocker so that it fits inside the second guide shim.

[running_sideways]

Originally Posted by TheRealSy90

YOU need to measure the lash between the camshaft lobe (with valve closed) and the top of the valve stem, and subtract the clearance you want. This is how you determine your shim thickness.


For dual guides, OEM guides are all the same size. Many people run dual oem guides with no issues at all.
However if you want, Tomei offers guide shims in different thickness than the OEM guides.
If they don't have a thickness you need you can order one larger and shave it down, or there's a company in Australia that can make tool steel guide shims to your specified size.
And remember to clearance the arm of the rocker so that it fits inside the second guide shim.

Well...I thought with hydro lifters you didn't really measure clearances between the cam and the rocker arms...I thought the only reason the shims were different sizes was to make sure the rocker arm fits square on cam...I guess I'm confused


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[slider2828]

I made a tool like that.... Its super easy...

http://www.sr20forum.com/general-sr2...view-sr20.html

[TheRealSy90]

Originally Posted by running_sideways

Well...I thought with hydro lifters you didn't really measure clearances between the cam and the rocker arms...I thought the only reason the shims were different sizes was to make sure the rocker arm fits square on cam...I guess I'm confused

I misread and assumed you had lost ALL of your shims.


Yes, you don't necessarily HAVE to measure clearance when running the hydro lifters and doing dual guides. I've done this personally on customer/friends engines as well as MANY other people without a single issue. It's proven and it works. However I'd only recommend this when running an oem, un-modified head. As in the valves/springs/retainers have never been upgraded or modified, clearances should all be as they came from the factory aside from normal wear in.


However, if YOU want to put in the time and work, you can measure each specific flat shim, and replace it with a oem/tomei/etc guide shim that matches it's size perfectly. And do this for every flat shim individually. This would be an even better method but isn't absolutely required.


As for the one flat shim that you're missing, if you decide to throw in all oem guides you'll be fine. If you decide to measure and calculate each one, then you'd have to measure from the valve stem on that one.


If it's a "built" head; as in upgraded valves, springs, lifters, angled valve job, lifter upgrade, etc etc. In that case I wouldn't guarantee that throwing in all oem guides would be good enough, and I'd recommend measuring the lash and ordering accordingly.

[TheRealSy90]

TLDR if you just threw in the Tomei cams, and everything else in the valvetrain is stock and unmodified/touched. Throw in all oem guides and go. If the Tomei cams are designed to drop in on a stock head, it should be fine.


If you want to take it even further, the lifters from the late model roller rocker sr20de usdm Sentra's are a drop in upgrade on det heads. They resist collapsing much better than our old lifters. Larger oil intake port, smaller oil release port.